In the related art, a vertical substrate processing apparatus that includes a process chamber for processing a substrate inside a substrate holder (susceptor), and performs substrate processing by supplying a reaction gas while heating a plurality of substrates in the process chamber held in a vertical direction by induction-heating the susceptor has been known (for example, in Japanese Patent Laid-open Publication No. 2007-095923). The substrate processing apparatus is configured to cover the entire periphery of the process chamber by a heat insulating material in such a manner that the substrate holder for holding the substrate is supported from a lower side by a lower heat insulating material, an inner heat insulating material is provided on a horizontal peripheral edge of the lower heat insulating material, and an upper heat insulating unit is provided above the substrate holder. Therefore, since the entire periphery of the process chamber is covered with the heat insulating material, homogenization of a temperature distribution of the process chamber is promoted due to a large heat insulating effect (heat retaining effect) of the process chamber.